This process relates generally to a process for recovering metals from metal-bearing materials, and more specifically, a process for recovering copper and other metals through high temperature pressure leaching in a pressure leaching vessel wherein a seeding agent is added to the pressure leaching vessel during the oxidation process.
Smelting is one approach for recovering metals, such as copper, from metal-bearing sulfide materials. Due to the high cost of smelting, the copper sulfide minerals in the ore body typically are first concentrated by flotation techniques to provide a smaller volume for smelting. The concentrate is then shipped to a smelter, which processes the concentrate pyrometallurgically at high temperatures to form a crude copper product that is subsequently refined to a highly pure metal.
The recovery of copper from copper sulfide concentrates using pressure leaching has proven to be a potentially economically attractive alternative to smelting. Pressure leaching operations generally produce less fugitive emissions than smelting operations, and thus, environmental benefits may be realized. Further, pressure leaching circuits may be more cost-effectively constructed on-site at a concentrator, eliminating the expense associated with concentrate transportation that smelting operations may require. Further, any by-product acid produced in the pressure leaching circuit may be used in adjacent heap leaching operations, thus offsetting the costs associated with purchased acid.
On the other hand, the application of pressure leaching may result in unacceptably high copper and precious metal losses. A significant cause of such metal losses has been identified when metal values become occluded by materials present in the pressure leaching vessel, such as, for example, hematite and/or other materials, rendering these metal values unavailable to subsequent processing, which results in these metal values being lost.
An effective and efficient method to recover copper from copper-containing materials, especially copper from copper sulfides such as chalcopyrite and chalcocite, that enables high copper recovery to be achieved at a reduced cost over conventional processing techniques and that enhances the recovery of precious metals from metal-bearing materials would be advantageous.
While the way in which the present invention addresses the deficiencies and disadvantages of the prior art is described in greater detail below, in general, according to various aspects of the present invention, a process for recovering copper and other metal values from a metal-bearing material includes various reactive and recovery processes. In a preferred aspect of the invention, a seeding agent is introduced to the metal recovery process, most preferably, during a pressure leaching process.
In accordance with an exemplary embodiment of the present invention, a process for recovering metal from a metal-bearing material generally includes the steps of: (i) subjecting a concentrate containing a metal value to a pressure leaching process, wherein the pressure leaching vessel is seeded with a seeding agent; and (ii) extracting the metal value from the product of the reactive process. In one aspect of an alternative embodiment of the invention, the seeding agent may be recycled residue that is introduced to the pressure leaching vessel. In general, the seeding agent is selected to enable the formation of a nucleation site for the crystallization and/or growth of solid species derived from the solution in which the reactive process occurs. In a further aspect of the present invention, other foreign material may be used as a seeding agent during pressure leaching. In an additional aspect of the present invention, a combination of seeding agents may be used during pressure leaching.
In yet another embodiment of the present invention, copper is recovered from a metal-bearing material. The copper-containing material is subjected to high temperature pressure leaching in a pressure leaching vessel, wherein a seeding agent is introduced into the pressure leaching vessel, which preferably is a multi-compartment pressure leaching vessel. The pressure leaching product may then undergo one or more subsequent conditioning and/or refining processes such that copper and/or other metal values may be recovered from the pressure leaching product or products.
The advantages of a process according to the various aspects of the present invention will be apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying drawing figures.